Insecticides and arachnicides

ABSTRACT

A non-toxic insecticide or arachnicide comprises insecticide or arachnicide in finely divided form comprising:  
     a) insecticidal or arachnicidal cellulosic material obtainable from the core of comcobs, and  
     b) optionally an attractant,  
     said cellulosic material interfering with the digestion of insects or arachnids and said insecticide or arachnicide being non-toxic to humans and is produced in finely divided form (e.g. particle size predominantly below 700 micrometres preferably 200 to 500 micrometres) so as to be carryable by the targeted insect (e.g. ants) or to collect on the exterior of the insect (e.g. the legs of a cockroach). Preferably the cellulosic material is obtainable from the core of corncobs of maize (corn) descended from any of the hybrids DK 446, DK 401, DK 442, DK 512, DK 560, DK 588, DK 591, DK 604, DK 628, DK 634 and DK 512 wx.

[0001] The present invention relates to insecticides and arachnicideswhich are non-toxic to human beings, domestic animals and livestock.

[0002] In our granted patent GB 2,311,464B it is disclosed that thecellulosic material obtainable from the core of the cob of a certainhybrid of maize (Zea mays, known as corn in the USA) is toxic to rodentsbut not to humans.

[0003] This hybrid is known as DK 446 and is obtainable from DekalbPlant Genetics (3100 Sycamore Rd, DeKalb, Ill. 60115 USA). It normallygrows to a height of 2.7 to 3.3 metres (9 to 11 feet) and normally has asingle giant ear of corn. It is commonly grown for use as cattle feed.

[0004] The cellulosic material obtained from the core of the cob of theabove hybrid has been analysed and has been found to consist ofessentially pure alpha cellulose, which is the naturally occurring formof cellulose. Alpha cellulose is generally recognised as a safe foodadditive with essentially no toxicity to humans and domestic animals.

[0005] It is believed that the different effects on rodents and humansare due to their different digestive systems, although there is someuncertainty about the precise mode of action of the above rodenticidalmaterial.

[0006] The above patent teaches that the rodenticide should preferablybe pelletised, the pellets having a diameter of 4 to 12 mm, preferably10 mm and a length of eg 10 to 30 mm. Such pellets are not effectiveagainst small, non-mammalian pests such as insects and arachnids.

[0007] U.S. Pat. No. 5,186,935 teaches that non-toxic insecticidalcompositions comprising diatomaceous silica and/or clamshells killinsects by scratching through the protective waxylayer, resulting indesiccation and dehydration. When such particles are injested by theinsect, death is accelerated by internal desiccation. The silica and/orclamshells are crushed to a particle size of less than 45 micrometresand coated with an attractant of honey and yeast.

[0008] U.S. Pat. No. 6,136,340 and also WO 97/02741 and WO97/02743disclose toxicant-free bait powder for insects such as ants, consistingessentially of spent grain reduced to particulate form. The spent grainis derived from corncobs by removing the core. No supporting data isgiven, no details of the mode of action are given and no details of thecorn or the particle size are given.

[0009] It has now been found that the cellulosic material of GB2,311,464B is also effective for the control of insects and arachnidswhen prepared in finely divided form and optionally combined with anappropriate bait attractant.

[0010] Accordingly the invention provides an insecticide or arachnicidein finely divided form comprising:

[0011] a) insecticidal or arachnicidal cellulosic material obtainablefrom corncobs, and

[0012] b) optionally an attractant,

[0013] said cellulosic material interfering with the digestion ofinsects or arachnids and said insecticide or arachnicide being non-toxicto humans.

[0014] In another aspect the invention provides a method of alleviatinginsect or arachnid infestation comprising depositing in the region ofinfestation an insecticide or arachnicide as defined above.

[0015] The above cellulosic material mainly comprises alpha cellulose. Asuitable commercial source is “Grit-O-Cobs” as supplied by The AndersonsInc., Ohio, United States of America.

[0016] The mode of mortality against insects and arachnids, while notyet fully clarified, is believed to be physical in nature: it isenvisaged that the alpha cellulose interferes with the digestive systemof the pest and prevents it from obtaining nourishment.

[0017] Because the above pesticidal material is not harmful to humans,livestock or domestic animals the invention has great advantages interms of safety and compatibility with the environment.

[0018] Pests which it is envisaged could be controlled by thecompositions of the invention include colonial insects of the orderHymenoptera, family Formicidae (which includes numerous species ofants), and insects of the order Isoptera, family Termitidae (whichincludes termites).

[0019] In particular the compositions of the invention are envisaged forthe control of the following species of ants:

[0020] Argentine ant—Iridomyrmex humilis

[0021] Big-headed ant—Pheidole megacephala

[0022] Black carpenter ant—Camponotus pennsylvanicus

[0023] Black imported fire ant—Solenopsis richteri

[0024] Brown carpenter ant—Camponotus castaneus

[0025] Cornfield ant—Lasius alienus

[0026] Florida carpenter ant—Camponotus abdominalis floridanus

[0027] Imported fire ant—Solenopsis geminata

[0028] Large yellow ant—Acanthomyops interjectus

[0029] Leaf cutter ant—Atta cephalotex

[0030] Leaf cutter ant—Atta sexdens

[0031] Little black ant—Monomorium minimum

[0032] (no common name)—Acromyrmex sp.

[0033] Odorous house ant—Tapinoma sessile

[0034] Pavement ant—Tetramorium caespitum

[0035] Pharaoh ant—Monomorium pharaonis

[0036] Red carpenter ant—Camponotus ferrugineus

[0037] Red imported fire ant—Solenopsis invicta

[0038] Small yellow ant—Acanthomyops clavige

[0039] Southern fire ant—Solenopsis xyloni

[0040] Texas leaf-cutting ant—Atta texana

[0041] Thief ant—Solenopsis molesta

[0042] In particular the compositions of the invention are envisaged forthe control of the following species of termites:

[0043] Arid-land subterranean termite—Reticulitermes tibialis

[0044] Common dry-wood termite—Kalotermes minor

[0045] Damp-wood termite—Paraneotermes simplicornis

[0046] Dry-wood termite—Criptotermes brevis

[0047] Dry-wood termite—Criptotermes rospigliosi

[0048] Dry-wood termite—Kalotermes schwartzi

[0049] Eastern subterranean termite—Reticulitermes flavipes

[0050] Formosan subterranean termite—Coptotermes formosanus

[0051] (no common name)—Ancistrotermes carithorax

[0052] (no common name)—Microtermes subhyalinus

[0053] Pacific damp-wood termite—Zootermopsis angusticollis

[0054] Southeastern dry-wood termite—Kalotermes snyderi

[0055] Southern dry-wood termite—Kalotermes hubbardi

[0056] Subterranean termite—Coptotermes testaceous

[0057] Subterranean termite—Heterotermes tenuis

[0058] Subterranean termite—Rhinotermes nasutus

[0059] Tree termite—Nasutitermes sp

[0060] Western dry-wood termite—Incisitermes minor

[0061] Western subterranean termite—Reticulitermes hesperus

[0062] An attractant which has been found particularly suitable for antsis carob oil or a volatile terpene component thereof. No addedattractant is needed for termites.

[0063] Accordingly one ant bait in accordance with the present inventioncomprises insecticidal or arachnicidal cellulosic material as definedabove (but preferably the woody ring material obtainable from the DK 446hybrid or a descendant thereof) impregnated with a volatile terpenecomponent of carob oil.

[0064] The insecticide or arachnicide can for example be deposited in ornear colonies of the ants, termites or other colonial insects or in thepath of an ant trail for example or can be distributed (preferablyuniformly) on infested pastureland or cropland land or on the floor ofinfested buildings for example. The dosage is not critical and ingeneral the optimum dosage can be determined by routine experimentation.The amount of pesticide needed to eradicate a colony will vary withfactors such as the identity of the pest, the size of the colony, andother factors.

[0065] It is envisaged that other species of ants and termites andindeed other families of colonial insects eg wasps are also susceptibleto the composition of the invention.

[0066] Another embodiment of the invention is suitable for the controlof cockroaches, in particular the following species:

[0067] American cockroach—Peeiplaneta americana

[0068] Brown-banded cockroach—Supella longipalpis

[0069] German cockroach—Blattella germanica

[0070] Oriental cockroach—Blatta orientalis

[0071] Smoky-brown cockroach—Periplaneta fuliginosa

[0072] Oriental cockroach—Blatta orientalis

[0073] Brownbanded cockroach—Supella longipalpa

[0074] Woods cockroach—Parcoblatta spp.

[0075] Australian cockroach—Periplaneta australasiae

[0076] Brown cockroach—Periplaneta brunnea

[0077] Asian cockroach—Blattelle asahinai Mizukobo

[0078] Surinam cockroach—pycnoscelus surinamensis

[0079] Florida Woods cockroach—Euridotis floridana

[0080] Cockroaches remain one of the most widespread and troublesomehousehold and commercial pests, in spite of the extensive use ofinsecticides, and German cockroaches in particular are responsible forthe transmission of disease and are commonly found indoors. Hence theuse of toxic compositions is undesirable.

[0081] An attractant which has been found particularly suitable forcockroaches is fish meal or a volatile amine component thereof.

[0082] Accordingly one cockroach insecticide in accordance with thepresent invention comprises cellulosic material as defined above (butpreferably the white core material obtainable from the DK 446 hybrid ora descendant thereon impregnated with a fishy amine.

[0083] The cockroach insecticide can be applied uniformly as a thick (eg5 mm or greater) dust on the floors of infested buildings or can bedeposited around the perimeter of the floor of an infested room eg to adepth of 20 to 30 mm where it is particularly effective becausecockroaches normally prefer to follow a peripheral path.

[0084] Other pests which, it is envisaged, could be controlled bycomposition in accordance with the invention include both insects andarachnids, including fleas, mites including spider mites and gall mitesticks, mosquitos, aphids and thrips for example.

[0085] Because the composition of the invention is in finely dividedform (eg a powder) either it tends to collect on the surface of eg thelegs of larger insects such as cockroaches, prompting the affectedinsect to remove the insecticide by eating it, or, particularly in thecase of colonial pests such as ants and termites, individual grains arepicked up and carried back to the colony (eg by worker ants) and sharedwith other inhabitants of the colony, a process known as trophallaxis.Because the insecticide of the invention takes effect only gradually itcan be widely distributed within the colony before killing the insects.

[0086] Preferably the particle size range of the insecticide is selectedto suit the species being targeted and can be determined experimentallyand/or by reference to the known physiology of the species, inparticular the carrying and eating capacity of the workers, for example.

[0087] Thus a particle size range of 80/60 (ie predominantly 180micrometres to 250 micrometres) is suitable for brown and black antsbecause particles of this size are large enough to be picked up byworker ants of these species but not too large to be eaten, whereas aparticle size range of 60/40 (ie predominantly 425 to 250 micrometres)is more suitable for pharaoh ants.

[0088] As will be understood by persons skilled in the art of powderpreparation, a particle size range of ‘A/B’ means particles capable ofpassing through a US Standard Sieve of mesh ‘A’ but not capable ofpassing through a US Standard Sieve of mesh ‘B’. The different USStandard Sieves have respective opening sizes which can be looked up instandard tables.

[0089] A particle size range of 80/60 (ie predominantly 180 micrometresto 250 micrometres) is suitable for cockroaches because such particlesare small enough to collect on the legs of cockroaches but sufficientlylarge to have a significant effect on their digestive system.

[0090] Other hybrids similar to the above DK 446 hybrid (especiallymaize hybrids characterised by normally growing to a height of 2.7 to3.3 metres (9 to 11 feet) and by normally having a single giant ear ofcorn) are envisaged to be useful sources of identical or similarcellulosic pesticidal material which is also usable in compositions inaccordance with the invention. Furthermore hybrids DK 401, DK 442, DK512, DK 560, DK 588, DK 591, DK 604, DK 628, DK 634 and DK 512wx, ordescendants thereof, all obtainable from Dekalb Plant Genetics, areenvisaged to be useful sources of identical or similar pesticidalmaterial.

[0091] Preferably the attractant, if present, is a natural product or isderived from a natural product. In certain embodiments the attractantcan be a semiochemical (ie a chemical that mediates an (in this caseattractant) interspecific or intraspecific interaction involving thetargeted pest) and is preferably a pheromone. Such embodiments have theadvantage over conventional compositions involving synthetic (andsomewhat volatile) chemical toxic agents that cellulose is inert andodourless and does not interfere with the effect of the semiochemical.

[0092] The insecticide or arachnicide can be made by bringing intoassociation a) a pest attractant b) said cellulosic material.

[0093] Preferably the cellulosic material is reduced to a finely dividedform with a range of particle sizes selected to optimise ingestion bythe targeted insect or arachnid. For example the particle sizes can bepredominantly less than 700 micrometres (preferably less than 500micrometres) and predominantly greater than 100 micrometres (preferablygreater than 200 micrometres).

[0094] The invention extends to compositions comprising any of thecellulosic insecticidal or arachnicidal materials identified above(particularly alpha celluloses), whether synthetic or obtained fromnatural sources.

[0095] Preferred embodiments of the invention are described below in thefollowing non-limiting examples.

EXAMPLE 1 Ant Bait

[0096] Woody ring material from the DK 446 hybrid (obtained from thehybrid by the method dislcosed in GB 2,311,464B) was classified to an80/60 size range (ie predominantly 180 micrometres to 250 micrometresparticle sizes) and mixed in a 1:1 weight ratio with Carob seeds(commercially available as an animal feed and obtainable from the pod ofthe Carob tree Ceratonia siliqua) and tumbled for 15 minutes in anairtight stainless steel drum. The tumbling procedure was repeated dailyfor four days and the product was then sifted to separate the white corematerial (now impregnated with carob oil from the carob seeds) from thecarob seeds.

[0097] The impregnated white core material was deposited in a colony ofblack sweet ants and it was observed that the worker ants carried offgrains of the material to the remaining ants in the colony. The colonywas eradicated in three days.

[0098] The product could be stored in triple-ply paper bags having aplastic liner (150 pound bursting strength) without loss of efficacy.

EXAMPLE 2 Termite Bait

[0099] Woody ring material from the DK 446 hybrid (obtained from thehybrid by the method dislcosed in GB 2,311,464B) was classified to an60/40 size range (ie predominantly 250 micrometres to 425 micrometresparticle sizes). Two kilograms of the finely divided cellulosic materialwas deposited in a colony of termites (after removing the top of thecolony with a pickaxe to provide access) and it was observed that thesoldier termites carried off grains of the material to the remainingtermites in the colony. The colony was eradicated in three days.

[0100] The product could be stored in triple-ply paper bags having aplastic liner (150 pound bursting strength) without loss of efficacy.

EXAMPLE 3 Cockroach Bait

[0101] Woody ring material from the DK 446 hybrid (obtained from thehybrid by the method dislcosed in GB 2,311,464B) was classified to an80/60 size range (ie predominantly 180 micrometres to 250 micrometresparticle sizes) mixed in a 5:1 weight ratio with commercially availablefish bone meal and tumbled for 15 minutes in an airtight stainless steeldrum. The tumbling procedure was repeated daily for five days and theresulting product was deposited in a region of cockroach infestation.The infestation was eradicated in 24 hours.

[0102] The product could be stored in triple-ply paper bags having aplastic liner (150 pound bursting strength) without loss of efficacy.

1. An insecticide or arachnicide in finely divided form comprising: a)insecticidal or arachnicidal cellulosic material obtainable fromcorncobs, and b) optionally an attractant, said cellulosic materialinterfering with the digestion of insects or arachnids and saidinsecticide or arachnicide being non-toxic to humans.
 2. An insecticideor arachnicide according to claim 1 wherein said cellulosic material isobtainable from corncobs of hybridised corn.
 3. An insectide orarachnicide according to claim 2 wherein said hybridized corn isdescended from any of the hybrids DK 446, DK 401, DK 442, DK 512, DK560, DK 588, DK 591, DK 604, DK 628, DK 634 and DK 512 wx.
 4. Aninsecticide or arachnicide according to claim 1 having particle sizespredominantly below 700 micrometres.
 5. An insecticide or arachnicideaccording to claim 4 having particle sizes predominantly below 500micrometres and predominantly greater than 200 micrometres.
 6. An antbait according to claim 1 having a particle size range selected from thegroup consisting of 80/60 (predominantly 180 micrometres to 250micrometres) and 60/40 (predominantly 425 to 250 micrometres).
 7. An antbait according to claim 1 comprising an attractant selected from thegroup consisting of carob oil and a volatile terpene component of caroboil.
 8. A cockroach bait according to claim 1 having a particle sizerange of 80/60 (predominantly 180 micrometres to 250 micrometres).
 9. Acockroach bait according to claim 1 comprising an attractant selectedfrom the group consisting of fishmeal and a volatile amine component offish meal.
 10. An insecticide or arachnicide according to claim 1 havinga semiochemical as a bait attractant.
 11. A method of alleviating insector arachnid infestation comprising depositing in the region ofinfestation an insecticide or arachnicide as claimed in claim
 1. 12. Amethod according to claim 11 wherein the particle sizes of theinsecticide or arachnicide are such as to enable targeted insects orarachnids to carry the insecticide or arachnicide particles to others ofthe targeted insects or arachnids.
 13. A method according to claim 11wherein the targeted insects are selected from the group consisting ofants and termites.
 14. A method according to claim 11 wherein theparticles are small enough to collect on the exterior of the targetedinsects or arachnids but sufficiently large to affect their digestivesystems.
 15. A method according to claim 14 wherein the targeted insectsare cockroaches.
 16. A method according to claim 11 wherein theinsecticide or arachnicide is deposited within a building used by humanbeings.